We propose a series of structured interviews and experimental studies examining adolescents' perceptions of the decisions that they make which can affect their risks of STDs. The first study will elicit open-ended descriptions of such decisions. Subjects will be directed to consider both "tactical" decisions (e.g., how to insist on condom use) and "strategic" ones (e.g., what kind of friends to seek). Their responses will be analyzed in terms of the content structure, and processes of the decisions described. The second study will ask elicit critiques of these decisions by other teens drawn from more or less similar backgrounds. These critiques will be analyzed in similar terms, in order to examine what additional sophistication teens might bring to decisions where they are not direct parties) and provide to one another). The next three studies examine the accuracy of adolescents' STD-related judgments, as well as the criticality of particular misconceptions. One study involves an open-ended elicitation of subjects' mental models of the risk processes involved in creating STD risks and controlling exposure to STDs and a comparison of these models to an expert model of these same processes. A second study examines the appropriateness of subjects' confidence in their beliefs. The third study asks for quantitative estimates of the STD risks in specific circumstances. The three studies are interrelated so as to provide an assessment of the robustness of the beliefs that are expressed. Particular attention will be paid to the "bugs" in teens thinking. The final study uses these results to develop and evaluate a risk communication, intended to help teens make these decisions. In addition to producing written communications, these cognitive studies will provide the empirical grounding for a computer- assisted interactive media intervention. The two approaches will be compared with one another in a large intervention conducted in primary care settings, as a way to provide age-and culture-appropriate information that medical professionals are too stressed to provide. Subjects will be sampled in equal amounts from high-risk and low-risk population. Each group will be divided equally by race/ethnicity. The studies as a whole will provide a multi-perspective picture of how teens conceptualize the risks of STDs and the decisions affecting those risks.